Ryan Nelsen believes West Ham have issued a statement of intent by tying Winston Reid to a new deal.
Tottenham are keen for striker Shaquile Coulthirst to continue his development out on loan after his spell at Southend.
The 23-year-old has spent four separate spells with Yeovil, and a stint with the Seagulls' rivals Crystal Palace, but is yet to appear for Spurs in the Barclays Premier League.
Leroy Lita has left the Amex Stadium to return to Swansea and Seagulls assistant Nathan Jones, who worked with Obika at Yeovil, was keen to bring in the Tottenham forward.
Manager Oscar Garcia told Brighton's official website: "Jonathan is someone we have been aware of for some time because Nathan has worked closely with him in the past at Yeovil and Charlton.
"It is known that we tried to bring him earlier in the season, but were not able to due to an injury, so we are pleased to have him here now."