Biden Uses NATO Summit to Assail Trump on Foreign Policy

President Biden used the closing of the NATO summit to issue a blistering attack on Donald J. Trump’s rejection of the value of alliances, and he declared for the first time that he had developed a strategy to interrupt the growing military and technological relationship between Russia and China.

In a wide-ranging news conference being watched to see how he handled himself amid questions about his age and acuity, Mr. Biden mixed defiance of his critics with several flubs.

But the session also served as a platform for him to show a command of foreign policy, including describing in detail the decisions he has made over three and a half years that have been punctuated by wars in Ukraine and Gaza.

He took credit for warning the Europeans of an impending invasion of Ukraine in late 2021 and early 2022, and for preparing NATO to provide arms and intelligence as soon as war broke out. And he used the moment to remind American voters that Mr. Trump’s first reaction to the invasion was to praise President Vladimir V. Putin.

“Here’s what he said,” Mr. Biden added, his voice dripping with sarcasm: “‘It was genius. It was wonderful.’”