I am trying to remember a book I read in the late 1990s/early 2000s that revolved around aliens assisting humans in colonizing another planet (possibly space station) through a wormhole made by the aliens. Nations of Earth (the same as contemporary nations, USA, Israel, Korea, China, etc.) each sent one spaceship along with the aliens as a delegation and were supposed to be unarmed, but the main character (definitely the captain of a ship, I believe it was the USA) realizes his ship has weapons on it, but is convinced to not discard them as other nations have taken the precaution of arming their ships as well. After traveling through the wormhole there are tensions between the various nations and some minor spaceship fights.
Partway through the novel, a space station belonging to the same nation as the main character ends up making its own wormhole and joining the delegations and the aliens. I cannot remember how it ends. I seem to remember that the alien spaceships use some sort of gravatics drive (strengthening and weakening gravity to maneuver).