• Defense Secretary Lloyd Austin canceled a trip to Brussels this week where he was supposed to attend meetings related to Ukraine's defense and NATO.
• Austin was hospitalized Sunday for bladder issues as he fights an ongoing battle against prostate cancer.
• The Ukraine meeting will be held virtually, but the Pentagon has not clarified the status of the NATO session.

Defense Secretary Lloyd Austin canceled a trip to Brussels this week where he was set to attend meetings related to Ukraine's defense and NATO, after his emergency hospitalization over the weekend.

The meeting on Ukraine will instead be held virtually. The Pentagon declined to confirm the status of the NATO meeting.

The change of plans comes during a week when Congress is trying to pass a bill for Ukraine aid and days after former President Donald Trump made controversial comments about possibly abandoning NATO allies, should he secure a second term.

Austin was taken to Walter Reed National Military Medical Center on Sunday afternoon due to "emergent bladder issues." The Defense secretary has been fighting prostate cancer and recuperating from surgery over the past few months.

On Monday, Austin went under general anesthesia for "non-surgical" procedures to address the bladder issue, according to Walter Reed doctors. They said that he would likely be able to resume his normal duties on Tuesday.

President Joe Biden is "not at all" concerned with Austin's ability to continue serving as Defense secretary, National Security Council spokesman John Kirby said Monday. Kirby noted that Biden had not yet spoken to Austin since he was hospitalized Sunday.

Doctors said late Sunday night that after undergoing tests and evaluations, Austin was admitted to the critical care unit.

Austin initially intended to maintain all of his functions and responsibilities. The Pentagon reported Sunday afternoon that he had brought to the hospital "unclassified and classified communication systems necessary to perform his duties."

Austin later transferred his duties to Deputy Defense Secretary Kathleen Hicks on Sunday evening.

The Pentagon said it will continue to provide regular updates on Austin's condition, trying not to repeat a recent mistake when the Defense Department failed to notify the White House when Austin was initially hospitalized for cancer surgery and later complications.

In January, Austin and his staff faced major backlash for not telling top government officials that the Defense secretary was admitted to the intensive care unit for reasons unknown at the time. Doctors later disclosed Austin's cancer diagnosis and details of his hospital visits.

Austin and the Pentagon apologized for the lapse in communication. This time around, the Defense Department has followed notification protocol to a T, a White House official told NBC News on Monday.

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