I don't think he blame Trump. He was just stating the situation he inherited from Trump. I didn't see anywhere in his statement that he said that Trump was to blamed.
"When I came into office, I inherited a deal that president Trump negotiated with the Taliban. Under his agreement, US forces would be out of Afghanistan by May 1st, 2021, just a little over three months after I took office, US forces that were already drawn down during the Trump administration from roughly 15,500 American forces to 2,500 troops in country. And the Taliban was at its strongest militarily since 2001. The choice I had to make as your president was either to follow through on that agreement, or be prepared to go back to fighting the Taliban in the middle of the spring fighting season. There would have been no ceasefire after May 1.
There was no agreement protecting our forces after May one, there was no status quo of stability without American casualties. After May one, there was only a cold reality of either following through on the agreement to withdraw our forces or escalating the conflict and sending thousands more American troops back into combat in Afghanistan, lurching into the third decade of conflict. I stand squarely behind my decision. After 20 years, I’ve learned the hard way that there was never a good time to withdraw US forces. That’s why we’re still there."
President largely blamed Afghans themselves for their current predicament
www.independent.co.uk