Michael Flynn resigned as President Donald Trump’s national security adviser on Monday night amid reported concerns by White House officials about his communications with Russia’s ambassador to the U.S., The New York Times reported Monday.

The Justice Department warned the Trump administration last month that Flynn has not been straightforward regarding the scope of his phone calls with Russian ambassador Sergey Kislyak, according to the publication.

DOJ is also concerned that the retired Army general could be vulnerable to Russian blackmail, the report states.

The Times reported that officials found that Flynn did not forthrightly relay to administration officials that he discussed sanctions related to Russia’s interference in the 2016 U.S. election with Kislyak during a phone conversation.

Flynn said in his resignation letter obtained by CNN that he spoke with his foreign counterparts, ministers and ambassadors as the incoming national security adviser in efforts to help facilitate a smooth transition into the new administration.

“Unfortunately, because of the fast pace of events, I inadvertently briefed the Vice President Elect and others with incomplete information regarding my phone calls with the Russian Ambassador,” he wrote.

“I have sincerely apologized to the President and the Vice President, and they have accepted my apology.”

The Government Accountability Office has urged the Department of Homeland Security to cooperate with the FBI in the completion of a formal bioforensics capability gap analysis.

GAO said Friday the capability gap analysis can help inform current and future bioforensics investments through the identification of needs and scientific and technical gaps.

DHS and FBI have worked to determine gaps in their bioforensics functions through an informal undocumented process, which makes it unclear whether all capability gaps have been identified, GAO added.

Auditors said DHS plans to roll out improved bioforensics measures in 2025 but the department faces challenges such as the need for a statistical framework that can interpret bioforensics analyses and present them in court settings.

DHS also needs to obtain suitable biological agents and DNA sequences to provide quality references for investigations.

GAO also recommended DHS to update the formal capability gap analysis periodically.

The government watchdog examined whether DHS and FBI have improved their capacity to track the source of a biological threat agent since the 2001 anthrax attack.

A group of eight Republican senators has written a letter to President Donald Trump asking him to pursue a “results-oriented” and “principled” Russia policy that would highlight the country’s activities in cyberspace, Syria and Ukraine.

Sens. Mike Rounds (R-South Dakota), Cory Gardner (R-Colorado), Jim Inhofe (R-Oklahoma), Todd Young (R-Indiana), Rob Portman (R-Ohio), Joni Ernst (R-Iowa), Susan Collins (R-Maine) and Lindsey Graham (R-South Carolina) jointly urged the Trump administration to maintain the current sanctions regime against Russia and Russian organizations, Rounds’ office said Thursday.

The lawmakers also called on the White House to condemn continued Russian aggression in Ukraine as well as counter Russia’s cyber and information warfare efforts against western democracies such as the attempted interference in the U.S. democratic elections process.

They said the U.S. should maintain an open dialogue with Russia on global initiatives related to nuclear arms control, anti-drug trafficking , counterterrorism and healthcare promotion.

“However, while we should seek common ground with Russia in the areas of mutual interest, we must never pursue cooperation with Russia at the expense of our fundamental interests of defending our allies and promoting our values,” the letter states.

A new Mitre study says the U.S. Navy needs a fleet size of 414 combat ships that would include 160 destroyers and cruisers, 72 attack submarines and 14 aircraft carriers, Breaking Defense reported Friday.

Sydney J. Freedberg Jr. writes Mitre’s 15-year shipbuilding plan for the Navy would cancel the Littoral Combat Ship program and replace it with new classes of ships such as frigates and magazine ships.

Mitre’s study suggests a “high-low mix” of a small number of high-end combat vessels and a large number of low-end warships such as magazine ships – MG(X) – and diesel-powered attack submarines.

The nonprofit organization recommended that the service branch continue to build nuclear-powered Virginia-class submarines at a rate of two vessels per year and replace the San Antonio-class amphibious transport dock vessels with either three modified Watson-class cargo ships or six Spearhead-class expeditionary fast transport ships.

Mitre also called for the Navy to prioritize the deployment of the Hyper-Velocity Projectile for use with electromagnetic railguns aboard destroyers and cruisers, the report added.