In a dramatic turnaround from his election campaign calls for the 16-year war to be brought to an end, Trump unveiled a new south Asia strategy designed to prevent a Taliban takeover of Afghanistan, target Islamic State and al Qaida and stop mass terror attacks in the USA.
And he said he was "confident" that Nato allies - which include Britain - would hike troops and funding in line with the US.
Cross, who's also a former president of the Armed Forces Christian Union told Premier: "Even Trump admitted, that living in the Oval office, you see things differently."
Defence Secretary Sir Michael Fallon welcomed the president's move, saying the allies must "stay the course" in Afghanistan.
But in a statement responding to the announcement, he gave no indication that the UK is considering an increase to its 500-strong deployment and stressed that an additional 85 troops were committed as recently as June.
Trump said American policy would now focus "not on nation-building but on killing terrorists". That's a strategy Cross disagrees with.
He told Premier: "Frankly I don't think that the right answer. I'm not suggesting that you don't need to attack brutal terrorists, but you don't destroy the idea by simply killing terrorists, other people simply move into that space.
"I'm not convinced this is a very coherent overall strategy for the long term."
Cross added that troops in Afghanistan will most likely be glad that Trump is reinvigorating the mission in Afghanistan.
He said: "I think they'll be encouraged that they're not a forgotten army. I know some British soldiers felt they were out there on a limb."
Cross told Premier how Christians should approach the issue: "From Christian point of view I don't think we should veer away from the fact that there is evil going on that there is sin and that we need to be prepared to step in into that and deal with it.
"More or less we have to somehow work our way through how you open up a dialogue, how you maintain a dialogue, how you find out what it is these people are trying to achieve."
Listen to Tim Cross speaking with Tola Mbakwe here:
